The major objectives of this project are the localization and interactions of tubulin and other fibrous proteins in the nerve ending. For this purpose, antibodies have been prepared aginst the proteins tubulin, desmin and the tau protein. Using immunoperoxidase methodologies, we are attempting to localize these proteins in the structures of the nerve ending. Other aspects of this work include the characterization of a second class of brain microtubule, the cold-stable microtubule. Our evidence indicates that a unique tau protein confers the property of cold-stability and we are testing this hypothesis by various approaches. The assembly of tubulin into an alternate structure, membranes, is under investigation.